Pain and stress in the human fetus

Fetal Pain in the First Trimester

Fetal pain perception has important implications for fetal surgery, as well as for abortion. Current neuroscientific evidence indicates the possibility of fetal pain perception during the first trimester (<14 weeks gestation). Evidence for this conclusion is based on the following findings: (1) the neural pathways for pain perception via the cortical subplate are present as early as 12 weeks gestation, and via the thalamus as early as 7–8 weeks gestation; (2) the cortex is not necessary for pain to be experienced; (3) consciousness is mediated by subcortical structures, such as the thalamus and brainstem, which begin to develop during the first trimester; (4) the neurochemicals in utero do not cause fetal unconsciousness; and (5) the use of fetal analgesia suppresses the hormonal, physiologic, and behavioral responses to pain, avoiding the potential for both short- and long-term sequelae. As the medical evidence has shifted in acknowledging fetal pain perception prior to viability, there has been a gradual change in the fetal pain debate, from disputing the existence of fetal pain to debating the significance of fetal pain. The presence of fetal pain creates tension in the practice of medicine with respect to beneficence and nonmaleficence.

Society for Maternal-Fetal Medicine Consult Series #59: The use of analgesia and anesthesia for maternal-fetal procedures

Pain is a complex phenomenon that involves more than a simple physical response to external stimuli. In maternal-fetal surgical procedures, fetal analgesia is used primarily to blunt fetal autonomic responses and minimize fetal movement. The purpose of this Consult is to review the literature on what is known about the potential for fetal awareness of pain and to discuss the indications for and the risk-benefit calculus involved in the use of fetal anesthesia and analgesia. The recommendations by the Society for Maternal-Fetal Medicine are as follows: (1) we suggest that fetal paralytic agents be considered in the setting of intrauterine transfusion, if needed, for the purpose of decreasing fetal movement (GRADE 2C); (2) although the fetus is unable to experience pain at the gestational age when procedures are typically performed, we suggest that opioid analgesia should be administered to the fetus during invasive fetal surgical procedures to attenuate acute autonomic responses that may be deleterious, avoid long-term consequences of nociception and physiological stress on the fetus, and decrease fetal movement to enable the safe execution of procedures (GRADE 2C); and (3) due to maternal risk and a lack of evidence supporting benefit to the fetus, we recommend against the administration of fetal analgesia at the time of pregnancy termination (GRADE 1C).

Society for Maternal-Fetal Medicine Consult Series #59: The use of analgesia and anesthesia for maternal-fetal procedures

Pain is a complex phenomenon that involves more than a simple physical response to external stimuli. In maternal-fetal surgical procedures, fetal analgesia is used primarily to blunt fetal autonomic responses and minimize fetal movement. The purpose of this Consult is to review the literature on what is known about the potential for fetal awareness of pain and to discuss the indications for and the risk-benefit calculus involved in the use of fetal anesthesia and analgesia. The recommendations by the Society for Maternal-Fetal Medicine are as follows: (1) we suggest that fetal paralytic agents be considered in the setting of intrauterine transfusion, if needed, for the purpose of decreasing fetal movement (GRADE 2C); (2) although the fetus is unable to experience pain at the gestational age when procedures are typically performed, we suggest that opioid analgesia should be administered to the fetus during invasive fetal surgical procedures to attenuate acute autonomic responses that may be deleterious, avoid long-term consequences of nociception and physiological stress on the fetus, and decrease fetal movement to enable the safe execution of procedures (GRADE 2C); and (3) due to maternal risk and a lack of evidence supporting benefit to the fetus, we recommend against the administration of fetal analgesia at the time of pregnancy termination (GRADE 1C).

The effect on pain level and comfort of foot massages given by mothers to newborns before heel lancing: Double-blind randomized controlled study

INTRODUCTION

In addition to pharmacological methods, non-pharmacological methods can also be used for reducing pain and increasing comfort during invasive procedures in newborn babies. This study was conducted to determine the effect on pain level and comfort of foot massages given by mothers to newborns before heel lancing.

METHODS

This is a double-blind randomized controlled experimental study. The sample consisted of 128 newborns including 64 in the intervention group and 64 in the control group. The Newborn Infant Pain Scale (NIPS) and Newborn Comfort Behavior Scale (NCBS) were used to collect the data, along with questionnaires for information on the newborn and mother. The researcher explained to each mother in theory how to do a foot massage at least 2 h before the heel lancing procedure. Mothers then drew random assignments to either an intervention group that would give a foot massage for 3 min with baby oil, or a control group that simply waited 3 min, immediately prior to the lancing.

RESULTS

It was determined that the foot massage performed by the mother reduced the pain level of babies, increased their comfort levels, and decreased their distress levels.

CONCLUSION

Nurses play an active role in defining and evaluating the newborn's responses to pain. It is thought that this study will guide nurses working in the clinic in reducing the acute pain that develops with invasive interventions performed on newborns and in preventing the negative effects of pain on the newborn.

[Feticide procedures in second and third trimesters terminations of pregnancy]

Performing a feticide as part of termination of late pregnancy is recommended in many countries. Feticide avoids a live birth of a severely affected premature newborn and prevents fetal pain. There are limited data on feticide procedures since only a few countries in the world authorize late termination of pregnancy. The objective of this review was to assess the most appropriate feticide procedure based on published data during the last thirty years. Administration of an initial fetal analgesia followed by a lethal lidocaine injection through the umbilical cord, under ultrasound guidance, appears to be the most effective, safe and ethical way to perform feticide. According to the current knowledge regarding the risk of fetal pain and survival of extremely preterm infants, a feticide should be discussed as early as 20-22 weeks of gestation.

Insights into the etiology and embryology of gastroschisis

The development of gastroschisis has long remained an area of interest and controversy. Successive theories about its pathogenesis are herein reviewed and discussed. Two historical assumptions, that omphalocele results from a persistent umbilical hernia, and that gastroschisis does not involve the umbilical cord, are dismissed. Therefore, one can envision gastroschisis for what it is, i.e. a ruptured physiological hernia. The causal agents for this intrauterine accident to occur are yet to be determined. Further bowel damage and complications can be explained by the mesenteric insult.

Fetal surgery and maternal cortisol response to stress. The myelomeningocele sheep model

BACKGROUND

Prenatal surgery represents a multifactorial stressor event for mother and fetus. The stress response to fetal surgery was evaluated by measuring maternal plasma and amniotic fluid (AF) cortisol levels in the myelomeningocele (MMC) sheep model.

SUBJECTS AND METHODS

Pregnant ewes (n = 8) underwent general anesthesia for MMC-induction (step 1: 75 d gestation), surgical defect repair (step 2: 110 d gestation), and delivery (step 3: 140 d gestation). Maternal blood samples were taken before surgery (surgical stage T1), after laparotomy and uterine exposure (surgical stage T2), at the end of the procedure (surgical stage T3). Fetal stress was evaluated by measuring cortisol levels in AF after hysterotomy at steps 1-3.

RESULTS

Maternal cortisol concentrations at T2 and T3 increased compared with T1 (p = 0.019 and p = 0.046). AF cortisol response increased from 1 to 3 surgical steps and during pregnancy. The AF cortisol level was lower than maternal serum levels (induction p < 0.001; repair p < 0.001; caesarean section p < 0.001).

CONCLUSIONS

Hysterotomy was the most stressful event in the ewes. Fetuses seemed to be partially protected from the high maternal cortisol levels. The fetal stress response to prenatal surgery increased with gestational age. Pain perception development, fetal maturation, and "pain memory" are probably associated with this increase.

Fetal Neurology: The Role of Fetal Stress

Fetal development and growth, as well as the timing of birth is influenced by the intrauterine environment. Many environmental factors causing the fetal stress can interfere with fetal development and leave long-term and profound consequences on health. Fetal glucocorticoid overexposure has primarily significant consequences for the development of the central nervous system. In response to an adverse intrauterine conditions, the fetus is able to adapt its physiology to promote survival. However, these adaptations can result in permanent changes in tissue and organ structure and function that directly ‘program’ predisposition to disease. Cardiometabolic disorders, behavioral alterations and neuropsychiatric impairments in adulthood and/ or childhood may have their roots in the fetal period of life. Fetal response to stress and its prenatal and lifelong consequences are discussed in this review.

How to cite this article

Kadić AS. Fetal Neurology: The Role of Fetal Stress. Donald School J Ultrasound Obstet Gynecol 2015;9(1):30-39.

Can healthy fetuses show facial expressions of "pain" or "distress"?

BACKGROUND

With advances of research on fetal behavioural development, the question of whether we can identify fetal facial expressions and determine their developmental progression, takes on greater importance. In this study we investigate longitudinally the increasing complexity of combinations of facial movements from 24 to 36 weeks gestation in a sample of healthy fetuses using frame-by-frame coding of 4-D ultrasound scans. The primary aim was to examine whether these complex facial movements coalesce into a recognisable facial expression of pain/distress.

METHODOLOGY/FINDINGS

Fifteen fetuses (8 girls, 7 boys) were observed four times in the second and third trimester of pregnancy. Fetuses showed significant progress towards more complex facial expressions as gestational age increased. Statistical analysis of the facial movements making up a specific facial configuration namely "pain/distress" also demonstrates that this facial expression becomes significantly more complete as the fetus matures.

CONCLUSIONS/SIGNIFICANCE

The study shows that one can determine the normal progression of fetal facial movements. Furthermore, our results suggest that healthy fetuses progress towards an increasingly complete pain/distress expression as they mature. We argue that this is an adaptive process which is beneficial to the fetus postnatally and has the potential to identify normal versus abnormal developmental pathways.

Fetal neurophysiology according to gestational age

More than 99% of the human neocortex is fashioned during intrauterine life, resulting in the fascinating diversity of fetal functions and activities. The objective of this review is to present the most significant neurodevelopmental events, as well as new findings about prenatal motor and sensory development.

What We have Learned from Fetal Neurophysiology?

The nervous system is one of the earliest emerging systems in fetal development. Due to progress of modern imaging technologies, such as ultrasound, a growing pool of information on the development of the central nervous system (CNS) and fetal behavioral patterns has been made available. The major events in the development of the CNS, fetal motor and sensory development as well as fetal response to stress are discussed in this review. The fetus is not entirely protected from harmful influence of the external factors. Postnatal follow-up studies have showed that many environmental influences causing the fetal stress can interfere with the fetal neurodevelopment and leave long-term and profound consequences on brain structure and function.

How to cite this article

SalihagićKadić A, Predojevic M. What We have Learned from Fetal Neurophysiology? Donald School J Ultrasound Obstet Gynecol 2012;6(2):179-188.

[Fetal pain and intrauterine analgesia/anesthesia--long-term pathologic effects, causes and alleviation of intrauterine pain]

The human fetus can suffer several presumably painful interventions perinatally and even before, during its intrauterine life. In the past years, scientific dispute concerning the existence of fetal pain and the need for its relief has expanded, and a heated social, political, religious, moral and philosophical debate has arisen, focusing mainly on the suffering experienced by the fetus during artificial abortion. In our two connected papers, medical scientific knowledge regarding fetal pain in the literature is reviewed. In the first article published in Orvosi Hetilap volume 150, issue 11, we defined pain and the neuroanatomical structures participating in subjective pain perception, as well as the development of these structures. Then, the objective indicators of intrauterine stress response (such as fetal neuroendocrine, cardiovascular, reflex and behavioral reactions) evoked by noxious stimuli were discussed. The present second article gathers the evidence of long-term pathologic effects caused by early-experienced pain and stress in animal models and humans. Finally, the potentially pain-evoking pre- and perinatal interventions are evaluated, as well as the analgetic/anesthetic methods that can be applied to intrauterine fetuses in everyday obstetrical practice.

Long-term impact of neonatal injury in male and female rats: Sex differences, mechanisms and clinical implications

Over the last several decades, the relative contribution of early life events to individual disease susceptibility has been explored extensively. Only fairly recently, however, has it become evident that abnormal or excessive nociceptive activity experienced during the perinatal period may permanently alter the normal development of the CNS and influence future responses to somatosensory input. Given the significant rise in the number of premature infants receiving high-technology intensive care over the last 20 years, ex-preterm neonates may be exceedingly vulnerable to the long-term effects of repeated invasive interventions. The present review summarizes available clinical and laboratory findings on the lasting impact of exposure to noxious stimulation during early development, with a focus on the structural and functional alterations in nociceptive circuits, and its sexually dimorphic impact.

Fetal pain and intrauterine analgesia/anesthesia: neuroanatomy, ontogenesis and physiology of pain perception

A magzat intrauterin élete során és perinatalisan számos, potenciálisan fájdalmas beavatkozáson eshet át. Az elmúlt években a magzati fájdalom létével és csillapításának szükségességével foglalkozó tudományos állásfoglalások kereteit túllépve széles körű társadalmi, politikai, vallási, erkölcsi, filozófiai vita bontakozott ki – leginkább a művi abortusz során a magzat által megélt szenvedést helyezve a középpontba. Munkánkban összefoglaljuk a magzati fájdalommal kapcsolatos orvosi szakirodalomban fellelhető ismereteket. Definiáljuk a fájdalmat, majd a szubjektív fájdalomérzet kialakulásában szerepet játszó neuroanatómiai struktúrák rövid ismertetése után utóbbiak ontogenezis során bekövetkező fejlődését ismertetjük. Ezt követően a noxa kiváltotta stresszválasz objektív (neuroendokrin-vegetatív, cardiovascularis, reflexes és viselkedési) komponensének intrauterin megfigyelhető bizonyítékait vesszük sorra.

FETAL ANAESTHESIA: IS THIS NECESSARY FOR FETOSCOPIC THERAPY?

Since Robinson and Gregory demonstrated the need to administer analgesia to preterm infants and the safety of such anaesthestic techniques in this specific patient population, pain in neonates and adequate analgesia have drawn more and more attention. Thanks to the outstanding work by Anand et al, it became increasingly clear that premature infants experience stress during invasive procedures and that as a consequence long-term neurodevelopmental status may be affected. Fetuses also demonstrate a stress response. Fetal analgesia can be administered efficiently, eliminating the fetal stress response. However, it remains unclear whether this results in improved neurodevelopment and improved long term outcome.

The effect of continuous morphine administration on maternal plasma oxytocin concentration and uterine contractions after open fetal surgery

OBJECTIVE

A major complication of open fetal surgery is prematurity. We propose that fetal and maternal stress/pain after surgery may affect the concentration of circulating oxytocin and the frequency of uterine contractions, thus increasing the risk of preterm delivery. The objective of this study was to test whether continuous morphine sulfate administration after open fetal surgery has an effect on maternal plasma oxytocin concentration and the frequency of uterine contractions.

METHODS

An established time-pregnant primate model for open fetal surgery was used. From the time of surgery until the end of the three-day study period, three animals received prophylactic antibiotics, a bolus of indomethacin, and a bolus of morphine sulfate (group I). Three other animals received the same prophylactic antibiotics and an i.v. bolus of indomethacin, as well as a continuous i.v. infusion of morphine sulfate throughout the entire study period (group II). Maternal blood samples were collected to determine oxytocin plasma concentrations. Oxytocin was measured by radioimmunoassay. Uterine activity was continuously recorded through an amniotic fluid catheter and quantified as number of contractions (10 mmHg increase from base line in intrauterine pressure) per hour (UCs/h).

RESULTS

The mean maternal plasma oxytocin concentration was higher (p < 0.01) and the number of uterine contractions more frequent (p < 0.05) in the group of animals with intermittent doses of morphine than in the group that received morphine continuously.

CONCLUSIONS

These data suggest that maternal plasma oxytocin concentration and uterine activity after open fetal surgery may be related to inadequate maternal/fetal analgesia/sedation.

Preemptive morphine analgesia attenuates the long-term consequences of neonatal inflammation in male and female rats

Despite mounting evidence on the importance of pain management in preterm infants, clinical use of analgesics in this population is limited. Our previous studies have shown that neonatal inflammation results in long-term alterations in adult somatosensory thresholds, characterized by decreased baseline nociceptive sensitivity, and enhanced hyperalgesia after a subsequent inflammatory insult. The present studies were conducted to determine whether preemptive morphine attenuates these negative consequences. At P0, pups received an injection of morphine sulfate before an intraplantar injection of 1% carrageenan. Control pups received either saline (SAL) followed by intraplantar carrageenan, morphine sulfate followed by intraplantar SAL, or SAL followed by intraplantar SAL. Preemptive morphine significantly attenuated neonatal injury-induced hypoalgesia in adolescence and adulthood. Similarly, morphine pretreated animals displayed significantly less hyperalgesia and recovered faster from a subsequent inflammatory insult compared with controls. Neonatal morphine had no significant effect on morphine analgesia in adulthood. Interestingly, neonatally injured animals that did not receive morphine displayed a significant rightward shift in the morphine dose-response curve in the absence of peripheral inflammation. Together, these results demonstrate that preemptive morphine significantly attenuates the long-term behavioral impact of neonatal inflammatory injury.

FETAL PAIN

The concept of fetal pain is becoming more and more relevant since the possibilities for invasive intrauterine treatment are increasing. However, there is much debate as to whether the fetus is mature enough to be able to perceive pain. But what is ‘pain’? One cannot determine whether a fetus feels pain unless one has a conception of what pain is. There is a difference in opinion about what pain really is and that is also the difficulty in studies on fetal pain: we cannot simply ask the fetus whether or not it feels pain. We can only give indirect evidence of possible harmful effects of stressful stimuli on the developing fetus. In this review we will first explore the meaning of ‘pain’. We will then discuss fetal anatomic, neurophysiologic and behavioural development and the responses which are thought to be required to experience pain. Finally, we discuss some ethical considerations and suggestions on fetal anaesthesia.

General vs local anesthesia for the percutaneous laser treatment of twin-twin transfusion syndrome

OBJECTIVE

The purpose of this study was to review our anesthetic experience in selective laser photocoagulation of communicating vessels (SLPCV) to treat twin-twin transfusion syndrome (TTTS).

STUDY DESIGN

A total of 266 consecutive eligible patients were studied. Twenty-seven patients (10%) underwent general anesthesia (GenA), 100 (38%) received total intravenous anesthesia (TIVA), and 139 (52%) received local anesthesia/conscious sedation (LocA). Maternal-fetal hemodynamic fluctuations were compared between groups.

RESULTS

Maternal blood pressure decreased significantly in all 3 groups during surgery (P < .0001) but was more evident in the GenA and TIVA groups (P < .0001). Maternal heart rate varied significantly in GenA (P = .02) but was constant in LocA and TIVA. There were no significant differences in fetal heart rate changes between the groups. Intraamniotic bleeding occurred more frequently with GenA and TIVA than LocA(P < .0001).

CONCLUSION

Local anesthesia is the safest anesthetic technique for SLPCV in TTTS patients.

Fetal surgery

Fetal surgery has emerged from the realm of medical curiosity into an exciting, multidisciplinary specialty now capable of improving patient outcomes for a wide variety of diseases. Recent advances allow prenatal providers to both accurately diagnose and treat many fetal anomalies while maintaining maternal safety. As the initial postnatal health care providers to the majority of these newborns, neonatologists need to be familiar with some of the more recent state-of-the-art procedures currently being used. In this review, the authors discuss the prenatal evaluation process and various operative approaches (ie, open hysterotomy, fetoscopy, and percutaneous) to conduct fetal surgery. They then analyze the effectiveness of some of the more established and experimental prenatal therapies that are being performed for a number of fetal anomalies, including twin-twin transfusion syndrome, thoracic malformations, airway obstruction, congenital diaphragmatic hernia, myelomeningocele, and aortic valve stenosis.

Non-pharmacological techniques for pain management in neonates

Significant progress in understanding the physiology, clinical correlates, and consequences of neonatal pain have resulted in greater attention to pain management during neonatal intensive care. A number of nonpharmacological therapies have been investigated, including nonnutritive sucking, with and without sucrose use, swaddling or facilitated tucking, kangaroo care, music therapy, and multi-sensorial stimulation. Although the efficacy of these approaches is clearly evident, they cannot provide analgesia for moderate or severe pain in the neonate. Further, some of these therapies cannot be effectively applied to all populations of critically ill neonates. Acupuncture, an ancient practice in Chinese medicine, has gained increasing popularity for symptom control among adults and older children. Acupuncture may provide an effective nonpharmacological approach for the treatment of pain in neonates, even moderate or severe pain, and should be considered for inclusion in a graduated multidisciplinary algorithm for neonatal pain management.

Fetal pain perception and pain management

This paper gives an overview of current science related to the concept of fetal pain. We have answered three important questions: (1) does fetal pain exist? (2) does management of fetal pain benefit the unborn child? and (3) which techniques are available to provide good fetal analgesia?

Ultrasound-guided radiofrequency-driven umbilical cord occlusion: an in-vitro study

OBJECTIVES

To assess the ability and safety of radiofrequency (RF) to induce cord thermal lesions using in-vitro perfused umbilical cords.

METHODS

Nineteen human term umbilical cords were cannulated at both ends and perfused continuously with saline serum in a saline serum bath (37 degrees C). The RF electrode was then inserted into the cord close to the umbilical vein. Different RF power and temperature controls were applied to determine the optimal RF procedure in terms of cord tissue injury and safety in nine experiments. The safety of RF procedures was investigated in ten cords by measuring temperature changes at different sites close to the RF electrode insertion and the impact of RF on cord narrowing was evaluated by continuous monitoring of intraluminal pressure. Subsequent histopathological analysis was carried out in all cases.

RESULTS

The optimal RF procedure reached a temperature of 100 degrees C in 10 min. RF produced a significant increase in intraluminal pressure (from 54.2 +/- 16.4 mmHg at baseline to 118.3 +/- 42.7 mmHg after 10 min, P < 0.05). There was no significant increase in temperature next to the site of insertion during the RF procedure. Histopathological analysis confirmed a > 30% decrease in cord and vein diameter. Cord tissue lesions were characterized by damage in the vessel walls and in the surrounding Wharton's jelly.

CONCLUSION

Our results suggest that RF might be a feasible and safe technique to induce occlusion of umbilical vessels. Further in-vivo experiments are needed to assess its ability to induce a complete occlusion of the umbilical cord.

Summary proceedings from the neonatal pain-control group

Recent advances in neurobiology and clinical medicine have established that the fetus and newborn may experience acute, established, and chronic pain. They respond to such noxious stimuli by a series of complex biochemical, physiologic, and behavioral alterations. Studies have concluded that controlling pain experience is beneficial with respect to short-term and perhaps long-term outcomes. Yet, pain-control measures are adopted infrequently because of unresolved scientific issues and lack of appreciation for the need for control of pain and its long-term sequelae during the critical phases of neurologic maturation in the preterm and term newborn. The neonatal pain-control group, as part of the Newborn Drug Development Initiative (NDDI) Workshop I, addressed these concerns. The specific issues addressed were (1) management of pain associated with invasive procedures, (2) provision of sedation and analgesia during mechanical ventilation, and (3) mitigation of pain and stress responses during and after surgery in the newborn infant. The cross-cutting themes addressed within each category included (1) clinical-trial designs, (2) drug prioritization, (3) ethical constraints, (4) gaps in our knowledge, and (5) future research needs. This article provides a summary of the discussions and deliberations. Full-length articles on procedural pain, sedation and analgesia for ventilated infants, perioperative pain, and study designs for neonatal pain research were published in Clinical Therapeutics (June 2005).

State of the science: procedural pain management in the neonate

Neonates in the neonatal intensive care unit experience painful procedures. Over the last 10 years, investigators have examined several pharmacologic and nonpharmacolgic treatment strategies to decrease or eliminate the pain associated with mechanical ventilation, endotrachial intubation, insertion of percutaneous or central venous lines, heel stick, and venipuncture. These procedures and others are addressed as well as the reported severity of pain associated with these procedures. Progress has been made in the past decade to establish evidence-based treatments that will help the clinician more effectively relieve neonatal stress and pain when performing many routine procedures.

The importance of ‘awareness’ for understanding fetal pain

Our understanding of when the fetus can experience pain has been largely shaped by neuroanatomy. However, completion of the cortical nociceptive connections just after mid-gestation is only one part of the story. In addition to critically reviewing evidence for whether the fetus is ever awake or aware, and thus able to truly experience pain, we examine the role of endogenous neuro-inhibitors, such as adenosine and pregnanolone, produced within the feto-placental unit that contribute to fetal sleep states, and thus mediate suppression of fetal awareness. The uncritical view that the nature of presumed fetal pain perception can be assessed by reference to the prematurely born infant is challenged. Rigorously controlled studies of invasive procedures and analgesia in the fetus are required to clarify the impact of fetal nociception on postnatal pain sensitivity and neural development, and the potential benefits or harm of using analgesia in this unique setting.

Development of a New Model to Investigate the Fetal Nociceptive Pathways

OBJECTIVE

The aim of the study was to develop an experimental model to investigate the fetal nociceptive pathways and fetal analgesia.

METHODS

We tested the electromyographic (EMG) response from the biceps femoris to electrical stimulation of the sural nerve in chronically-prepared fetal lambs with and without sufentanil.

RESULTS

An EMG response could be recorded 140 ms after the electrical stimulation above a threshold of current's intensity. The response presents the characteristics of a nociceptive flexion reflex. The reflex magnitude increased with the stimulus intensity. Sufentanil decreased the response. Bradycardia was noted 10 s after the stimulation and was not observed after sufentanilinfusion. Catecholamine concentrations were not altered by the stimulation.

CONCLUSION

Our study shows that a nociceptive flexion reflex can be recorded in the ovine fetus. We suggest that this reflex can be used as a new tool to study the ontogenesis of the nociceptive pathways and the effects of analgesic drugs during fetal life.

Managing twins discordant for fetal anomaly

An excess of structural anomalies is observed in twins compared to singletons. Approximately 1-2% of twin pregnancies may face the dilemma of expectant management versus selective termination following diagnosis of an anomaly affecting only one fetus. If the option of selective fetocide is considered, the main variable determining the technique to achieve this aim is chorionicity. In a dichorionic pregnancy, passage of substances from one twin into the circulation of the co-twin is unlikely due to the lack of placental anastomoses, hence KCl can be injected safely into the circulation of the affected twin to produce fetal asystole. In monochorionic twin pregnancies, selective termination needs to be performed by ensuring complete and permanent occlusion of both the arterial and venous flows in the umbilical cord of the affected twin, in order to avoid acute haemorrhage from the co-twin into the dying fetus, which may lead to death or organ damage. Bipolar cord coagulation under ultrasound guidance is associated with approximately 70-80% survival rates.

Pain and stress in the human fetus

It is not known if the fetus can actually feel pain, but noxious stimulation during fetal life does cause detectable stress responses. These responses cause both short and long-term changes in the central nervous system, which can affect subsequent pain behaviour. Reducing the stress response is known to be beneficial in children and adults and recent evidence suggests this is also true for the fetus. However, the optimal amount of suppression required and the best method of achieving this (opioid or regional anaesthesia techniques) remain unknown. Prevention and treatment of pain is a basic human right, regardless of age, and if the technique of fetal surgery is to progress then a greater understanding of nociception and the stress response is required.

Fetal surgery, anaesthesiological considerations

PURPOSE OF REVIEW

Refined techniques and skills have enabled sophisticated prenatal diagnosis in utero and resulted in the newly evolving specialty of fetal surgery in a few centres worldwide. Most of the procedures performed today have been preceded by extensive experimental research in animals, whereas fetal anaesthesia is mainly based on clinical experience and a few studies performed in pregnant sheep.

RECENT FINDINGS

Major limitations of fetal surgery include the high frequency of preterm labour and delivery which may offset any fetal benefit of the surgical procedure. The development of more potent tocolytic drugs than the drugs currently available may thus be compared to the meaning of potent immunosuppressive agents in organ transplantation. Fetal mortality and maternal morbidity consequently lead to a more cautious way of treatment, as with the development of endoscopic fetal surgery.

SUMMARY

The invasive fetal surgery is still considered as being in a research stage in most cases. Therefore most procedures are performed as minimally invasive, avoiding substantial risks by accessing the uterus through minimal openings. Some new devices are under investigation for monitoring the myometrial electrical activity and mechanical contractility and the fetal electroencephalogram, the continuous monitoring of the fetal arterial oxygen saturation, PO2 and PCO2, and for monitoring fetal cerebral oxygenation, blood volume and blood flow by near infrared spectroscopy.

Effects on the fetus and newborn of maternal analgesia and anesthesia: a review

PURPOSE

To review the effects of maternal anesthesia and analgesia on the fetus and newborn.

METHODS

An on-line computerized search of Medline, Embase, and the Cochrane Collaboration via PubMed was conducted. English language articles were selected. The bibliographies of relevant articles and additional material from other published sources were retrieved and reviewed.

PRINCIPAL FINDINGS

No one test clearly separates the effects on the fetus/newborn, if any, of maternally administered medication during labour and delivery, or during surgery for non-obstetric indications. Supposition in this regard is limited in part by methodology previously used to study the transplacental passage of various drugs. This work needs to be repeated using a human model. Routine maternal supplemental oxygen administration is being questioned in light of research showing that free radical generation and oxidative stress are implicated as the underlying mechanisms in several neonatal conditions. Maternal hypotension is associated with neonatal acidemia and base excess correlates with neonatal outcome. Common postpartum analgesics transfer minimally into breast milk. Maternal or fetal surgery conducted during pregnancy necessitates modification of both anesthetic and surgical approaches. The key to resuscitation of the fetus is resuscitation of the mother: intra-uterine maneuvers, including perimortem Cesarean section, aim to reverse treatable causes of fetal asphyxia, restore fetal oxygenation, and correct fetal acidosis.

CONCLUSIONS

The well-being of the infant is a major criterion for evaluating the anesthetic management of pregnant women. Many tools exist to assist with this determination for the fetus, whereas few are available to evaluate the newborn.

Fetoscopic temporary tracheal occlusion for congenital diaphragmatic hernia: prelude to a randomized, controlled trial

OBJECTIVE

As previously reported, high postnatal mortality seen in fetuses with congenital diaphragmatic hernia (CDH) with liver herniation and low lung-to-head ratio (LHR) appears to be improved in fetuses who undergo fetoscopic temporary tracheal occlusion (TO). To test whether further evolution of this technique produces results that justify a randomized controlled trial comparing prenatal intervention to postnatal care, the authors analyzed 11 additional cases and the cumulative experience with 19 cases.

METHODS

The authors analyzed retrospectively the outcome of 11 new and 8 previously reported cases of fetoscopic temporary tracheal occlusion. Various factors were studied including maternal morbidity, antenatal outcome, physiologic lung response, and neonatal course.

RESULTS

Temporary TO can be accomplished using 3 5-mm radially expanding uterine ports without hysterotomy. Obstetric morbidity included mild pulmonary edema in 6 cases, chorioamniotic separation and premature rupture of membranes in 12 patients, and preterm labor and delivery in all patients. Thirteen of 19 (68%) neonates survived for 90 days after delivery; one died in utero, and 5 died after birth. Late mortality included one death caused by sepsis and 2 by complications associated with tracheostomies. Morbidity from gastroesophageal reflux requiring Nissen fundoplication, tracheal injury requiring repair or tracheostomy, and recurrent hernias after diaphragmatic repair were characteristic in longterm survivors.

CONCLUSIONS

Fetoscopic temporary TO may improve outcome in poor-prognosis fetuses with CDH. However, complications related to tracheal dissection, premature delivery and late morbidity are significant. This experience has led to simpler techniques for fetoscopic tracheal occlusion and to an National Institutes of Health-sponsored randomized controlled trial comparing fetoscopic tracheal occlusion with optimal postnatal care.

Feticide during second- and third-trimester termination of pregnancy: opinions of health care professionals

OBJECTIVE

To study the opinions of professionals on feticide being performed as the first step of late termination of pregnancy (TOP).

SETTING

Tertiary care obstetrical unit with policy of routine feticide in late TOP.

METHOD

Questionnaire survey.

RESULTS

101/109 professionals responded (23 midwives, 22 doctors, 24 nurses, 21 auxiliaries, 9 others). 90 had heard of feticide, 83 knew about how and 38 about when the procedure was done. When asked about what the goals of feticide were, 94 respondents quoted, 'preventing parents from facing neonatal agony', 73 'avoiding fetal pain', 85 'preventing labor ward staff from facing neonatal agony', and 60 'complying with legal rules'. 54 respondents thought feticide was beneficial to their patients or improved their own professional practice, and 71 declared the procedure was emotionally positive, yet stressful. 48 respondents declared lacking information on feticide. Respondents who had attended to feticide at least once (n = 59) knew more on feticide, and were more positive on the impact feticide had on their practice than those who had never attended a feticide (n = 42).

CONCLUSIONS

In a highly specialized center, professionals had positive opinions on feticide, expecting it would avoid fetal or neonatal agony and pain.

The effects of analgesia in the vulnerable infant during the perinatal period

Although our knowledge of pain and its management in the perinatal period has increased, little is known about the first hours and days of life when major physiologic transition events occur. Prematurity and critical illnesses further complicate analgesic use during this time. Increased morbidity and mortality have been shown in infants receiving placebo infusions after surgery compared with infants with analgesia, highlighting the negative consequences of pain in infants. Opioids can help promote hemodynamic stability, promote respirator synchrony, and decrease the incidence of grade III & IV intraventricular hemorrhage in ventilated preterm neonates. Long-term follow-up studies suggest improved behavioral and cognitive outcomes in children given morphine infusions during NICU confinement. The necessity of fetal analgesia is dictated by the ability of the fetus to feel pain and by the adverse effects of noxious stimuli on future sensory development. Effects of drugs given to the pregnant woman on the (preterm) newborn might be influenced by decreased or absent transplacental transport, compression of the umbilical cord during delivery, or diminished blood flow in the placenta in pre-eclamptic women, resulting in higher serum concentrations. Pharmacokinetics and drug metabolism change in the last trimester, and pain sensitivity may be altered after 32 weeks of gestation. Consequently, dose and dose interval may vary considerably between neonates and within an individual during the first days of life. This subpopulation is not homogenous, and drug doses in a term neonate with a postnatal age of 2 weeks may be quite different from those at birth and are certainly different from those in a premature neonate. Size must be disentangled from age-related factors when examining developmental pharmacokinetic parameters. There are no longitudinal studies published investigating the pharmacokinetic properties of any analgesic more than once per infant. Polymorphisms of the genes encoding for the enzymes involved in the metabolism of analgesics or in genes involved in receptor expression may contribute to the large interindividual pharmacokinetic parameter variability. Polymorphism of the human mu opioid receptor has not yet satisfactorily explained pharmacodynamic variability.

Vulnerability of the developing brain. Neuronal mechanisms

Despite the improved survival of tiny preterm neonates, their neurodevelopmental outcomes remain a cause for grave concern. The authors propose two primary mechanisms leading to enhanced neuronal cell death in the immature brain: (1) NMDA-mediated excitotoxicity resulting from repetitive or prolonged pain, and (2) enhanced naturally occurring neuronal apoptosis during early development due to multiple metabolic stresses or lack of social stimulation. The pattern and magnitude of abnormalities will depend on genetic variability as well as the timing, intensity, and duration of adverse environmental experiences. Thus, cumulative brain damage during infancy will finally lead to reductions in brain volume, abnormal behavioral and neuroendocrine regulation, and poor cognitive outcomes during childhood and adolescence. The public health and economic importance of preventing or ameliorating the subtle brain damage caused by these mechanisms cannot be overestimated. This certainly justifies concerted efforts by neuroscientists and clinicians to investigate the mechanisms underlying early neuronal injury, to minimize the impact of adverse experiences and environmental factors in neonates, and to develop novel therapeutic strategies for improving the cognitive and behavioral outcomes of ex-preterm neonates.

Funipuncture for fetocide in late termination of pregnancy

The most widely used method for fetocide in late termination of pregnancy for fetal abnormalities (TOPFA) consists of injecting of potassium chloride (KCl) into the fetal heart and is likely to be painful after 22 weeks of gestation. We studied ten consecutive women undergoing TOPFA between 22 and 38 weeks. This technique for fetocide consisted of a single umbilical vein puncture under ultrasound guidance with injections of sufentanil 5 microg followed by KCl 2 g. No electrocardiographic modifications could be observed and maternal plasma potassium levels did not show any significant variation throughout the procedure. Fetal umbilical phlebotomy for fetal analgesia followed by fetocide therefore appears to be a safe procedure for the mother and allows the fetus to die without pain when late termination of pregnancy (TOP) is indicated.